A U.S. Marine was killed in a skirmish with Islamic State in northern Iraq on Saturday, making him the first American combat casualty in an attack by the extremist group in that country, U.S. and Iraqi officials said. The unidentified Marine died after Islamic State fighters fired rockets at a recently established base near Makhmour, on the outskirts of the region of Kurdistan, according to an e-mailed statement from the Pentagon. Several other Marines were being treated for injuries. Last October, a member of a U.S. special operations team was killed during a raid to free hostages of Islamic State in Hawija, in northern Iraq. Iraqi General Najim Abdullah al-Jabouri said Saturday’s attack wasn’t a surprise. “There is no safe place in Iraq,” he said. “Even the Green Zone in Baghdad, which houses the U.S. Embassy, is being targeted by rockets.’